Various types of devices exist for orthotic management of lower limb biomechanical deficits. For example, one type of orthotic ankle joint device includes a joint component with a splint mounting and a stirrup component that pivots relative to the joint component, providing resistance to dorsiflexion and plantarflexion pivotal movements away from a relatively central equilibrium (also termed “neutral” herein) ankle alignment angle of the wearer's lower leg with respect to the ankle, at which angle there is no net biasing force on the device.
To adapt an orthotic ankle joint device to the physiology and condition of the individual wearer, it is advantageous to adjust or tune the equilibrium ankle alignment angle, plantarflexion resist torque, and dorsiflexion resist torque. In addition, it may be advantageous to alter the angle versus torque behavior of the component through the gait cycle to provide support for specific musculoskeletal deficits. Certain existing devices permit adjusting such parameters. However, the ability to adjust each parameter independently of the others is desirable for ease of use and avoidance of inadvertent miscalibration.
A need therefore exists for an orthotic ankle joint device providing independently adjustable resistances to plantarflexion and dorsiflexion, equilibrium ankle alignment angle, and maximum limits on dorsiflexion and plantarflexion movements from the equilibrium ankle alignment angle. In addition, in existing orthotic ankle joint devices, it can be difficult if not impossible to set dorsiflexion resistances that are stiff enough to stabilize the wearer's ankle and knee against hyperflexion while at the same time soft enough to permit natural movement of the joint in a wearer's walking gait. An orthotic ankle joint device to address this challenge is also needed.